Use of Multiple Frequencies of Ultrasound in Midair Haptic Stimulation

We proposed a tactile stimulation method using multiple frequency ultrasound to shift the ultrasound focal point without changing the phase. This method can be presenting stable stronger tactile stimuli than any conventional stimulation method using phase switching. In the user study, it was found that the stimulus of the proposed method was perceived significantly stronger at the palm than that of conventional methods in 200 Hz.